Atomic number 38
Strontium
Alkaline earth metal
In the real world
Quick facts
- Atomic mass
- 87.620
- Group
- 2
- Period
- 5
- State (STP)
- solid
- Electronegativity
- 0.95
- Common ox. states
- +2
Properties
[Kr] 5s²
- Ionization energy
- 549.5 kJ/mol
- Electron affinity
- 5.0 kJ/mol
- Melting point
- 1050.00 K (776.9 °C)
- Boiling point
- 1655.00 K (1381.8 °C)
How dangerous is it?
A soft, silvery metal that reacts with water and air, so the pure metal is kept away from both. The strontium most people meet, in fireworks and toothpaste minerals, is harmless.
- FlammableImmediate
Freshly cut metal and strontium powder can catch fire in air, burning with a bright red flame. (as a fine powder or fresh cut, not a stable lump)
Cut and stored carefully under oil, with the powder kept away from sparks and heat.
- ReactiveImmediate
The fresh metal reacts with water and moist air, giving off hydrogen gas as it corrodes. (the reactive form is the pure metal, not the everyday strontium compounds)
Stored under oil or in a sealed, dry container to keep water and air away.
How it bonds
Strontium loses both 5s electrons to make Sr²⁺ in salts (SrCO₃, SrCl₂). Its compounds give the bright crimson color in fireworks. Sr-90, a fission product, is dangerous because it tracks calcium and lodges in bone.
